How to Chop an Onion Fast Without Crying

Chopping an onion doesn’t have to take forever. You can chop an onion in less than two minutes, and you can do it without crying! Get these easy tips, and start chopping onions like a pro!

How to Chop an Onion Fast Without Crying!

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Does chopping onions take you forever? Like, you don’t want to cook anything with onions in it, forever? Do they make you cry? And then you can’t get the smell off your hands? I have got the answers for you!

Follow These Steps to Quickly Chop an Onion Without Crying

Chopping an onion doesn’t have to take up most of your dinner prep time. In fact, you can do it in under two minutes!

Before you start chopping the onion, wash it under cool running water and pat it dry with paper towels or a clean dish towel. Peel off the outer papery layer of the onion skin. Then cut off the root end of the onion (the end with the hairs).

Place the onion, cut side down, on a cutting board, and slice it in half. Carefully peel off the outer layer of the onion. This layer is usually tough, and should be discarded. Now place the onion, cut side down on your cutting board.

For a fine dice, slice the onion lengthwise (with your knife held horizontal, parallel to the cutting board). Do not cut all the way through the onion, leave about 1/2 inch uncut. This will hold the onion layers together, so you can cut them all at the same time.

Next, make slices down the length of the onion (from the root end towards the tip), leaving the tip of the onion uncut. If you want smaller onion pieces, make these cuts closer together. If you want larger onion pieces, make these cuts farther apart.

Finally, slice the onion across the cuts you just made and the onion chunks should just fall apart!

How to Slice an Onion

If you want onion slices instead of chopped or diced onion, you’ll want to do things just a little differently. Wash, dry, and cut the onion in half just like you would to chop the onion (see the description above).

Then place the onion, cut side down, on your cutting board. Slice the onion from root to tip, leaving the tip of the onion uncut, just like in Step 2 above. This will give you nice even onion slices that will cook evenly. Then slice off the end of the onion, and your onion slices should fall apart.

Need some more tips? Check out the National Onion Association.

Why do Onions Make You Cry?

Onions can make your eyes burn and water. Why on earth does that happen?

Onions take up sulfur out of the ground as they grow. They store sulfur as part of a protein – S-1-propenyl-L-cysteine sulfoxide. When you cut an onion, you’re breaking open some of the onion’s cells. When these cells break, they release water and an enzyme called allinase. That enzyme (allinase) turns the sulfur-containing protein into 1-propenyl sulfenic acid.

That still isn’t our crying culprit. There’s another enzyme, called lachrymatory-factor synthase that turns this sulfenic acid into propanethial S-oxide. Which still isn’t what makes you cry! Propanethial S-oxide quickly evaporates into a gas. And when that gas gets into your eyes, it reacts with the water on the surface of your eyes. Then it turns into sulfuric acid.

Now we’ve got the problem! Sulfuric acid in your eyes will make them burn and sting. Your body’s natural response to that is to produce lots of tears to get the sulfuric acid out. Onions have all these compounds to make sulfuric acid to help protect them against predators. What kind of predators might eat onions? Anything that eats plants (herbivores)!

Got all that? Here’s the short version:

S-1-propenyl-L-cysteine sulfoxide in onions + allinase = 1-propenyl sulfenic acid
1-propenyl sulfenic acid + lachyrmatory-factor synthase = propantehial S-oxide
Propanethial S-oxide + your eyes = sulfuric acid
Sulfuric acid + your eyes = tears

Let’s try it a little different way:

Onions store sulfur inside their cells as part of a protein.
When the cells are cut open, that protein reacts with an enzyme to form an acid.
Then the acid reacts with another enzyme to form a gas.
When the gas gets into your eyes, it turns into sulfuric acid.
The sulfuric acid is what makes you cry.

Now that we have the chemistry out of the way…

Some people seem to be more affected by the onion’s natural protective mechanism than others. The type of onion you are using can make a big difference. Remember, these things that make you cry are also what gives an onion its flavor. So mild or sweet onions (like yellow onions) should have less of the sulfur-containing proteins, and should barely make you cry at all. If you’re using onions with a stronger flavor (like red onions), be sure to have some tissues close by!

(Check out these references for more information on the onion’s chemical reactions: University of Bristol School of Chemistry, Library of Congress, National Onion Association, and Scientific American)

Tips to Keep From Crying

There are lots of “quick fixes” on the internet that are supposed to help keep you from crying while you’re chopping an onion. Frankly, many of them don’t work, or are just plain impractical. There is a fun article on lifehacker that compares a bunch of these tricks. Here are my best suggestions.

Use a sharp knife. No matter what, when you cut onions you’re going to break open cells and start that chemical reaction we just talked about. But if you use a sharper knife, you’ll damage fewer cells, and perhaps release less of the sulfur proteins. Maybe. Anyway, you should always use a sharp knife.
Freeze the onion for 15 minutes before cutting. No one is exactly sure how this works. Some people think that this slows down the lachrymatory-factor synthase enzyme. Others think that when it is cold, the propanethial S-oxide can’t evaporate into a gas as quickly. (So you can finish chopping before you start crying.) No matter what the reason, this really does seem to work! But you do need to plan ahead, by about 15 minutes, to give your onion time to chill.
Refrigerate the onion for 30 minutes before cutting. This accomplishes the same thing as freezing for 15 minutes, but it does take longer. You shouldn’t store your onions in the refrigerator, they’ll get mushy and rot quickly.
Wear goggles. If you have a pair of goggles that fit firmly around your eyes so they don’t let any of the irritating gas in, you should be able to keep from crying when you chop an onion. Not many people have these handy. If you wear glasses, it can be hard to find goggles that fit over your glasses, and your glasses will get steamy inside the goggles.
Wear contact lenses. Some people think that wearing contact lenses helps to keep too much of the irritating gas from coming in contact with your eyes. Your eyes have their own little shields, so to speak. I wear contacts, and I rarely have trouble when I’m chopping onions. It could just be a coincidence.
Wash your hands right away. You will always end up with some “onion juice” on your hands after chopping an onion. If you accidentally rub your eyes with your onion-y hands, you’ll be introducing those painful molecules directly into your eyes! Ouch! Be sure to wash your hands right away after handling any onions.

If washing your hands doesn’t get all of that onion smell out, try rubbing them with lemon juice or salt, or try a piece of stainless steel.

Store Extra Onion

A recipe may not always call for an entire onion. (One medium onion is about one cup of chopped onion.) If you don’t need to use a whole onion, you can still save it for later. Wrap any unused onion tightly in plastic, and store in your refrigerator for 7-10 days. If you need to store cut onions for longer, freeze them. Simply chop them up, and place in zip-top freezer bags. Label the bags, and freeze your onions. You can pull out as much or as little as you need for a recipe. I try to keep a quart-sized freezer bag full of chopped onion in my freezer. It makes meal prep go just a little bit faster! Use the frozen onion within 12 months.

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